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Wound Healing and Repair

Overview

Wound healing is a complex and dynamic process of replacing devitalized and missing cellular structures and tissue layers.
The human adult wound healing process can be divided into 3 or 4 distinct phases. Earlier authors referred to 3 phases—inflammatory, fibroblastic, and maturation,
which has also been denoted as inflammatory, proliferation, and remodeling—and this is maintained by some authors.
In the 4-phases concept, there are the hemostasis phase, the inflammatory phase, the proliferation phase, and the remodeling phase. In the 3-phases approach, the hemostasis phase is contained within the inflammatory phase.

Not only do authors vary the number of phases, they also denote differences in the phase descriptors used; they may designate phases as the hemostasis phase, inflammatory phase, proliferation phase, and remodeling phase, or they may refer to the hemostasis phase, inflammatory phase, granulation phase, and maturation phase.
Therefore, certain phases have more than one name, such as remodeling or maturation and proliferation or granulation.
 As our understanding of wound healing progresses, further phases and subphases may well be delineated.

Within these broad phases are a complex and coordinated series of events that includes chemotaxis, phagocytosis, neocollagenesis, collagen degradation, and collagen remodeling. In addition, angiogenesis, epithelization, and the production of new glycosaminoglycans (GAGs) and proteoglycans are vital to the wound healing milieu. The culmination of these biological processes results in the replacement of normal skin structures with fibroblastic mediated scar tissue. For more information on wound healing, visit Medscape’s Wound Management Resource Center.

This process can go awry and produce an exuberance of fibroblastic proliferation with a resultant hypertrophic scar, which by definition is confined to the wound site. Further exuberance can result in keloid formation (see image below), in which scar production extends beyond the area of the original insult. The collagen is thicker, more irregularly arranged, and more often causes pain. In a hypertrophic scar, the collagen is thinner and arranged more parallel to the wound. Furthermore, hypertrophic scars occur in all races, although less so in young and elderly persons. Hormonal changes may have an impact. Keloid scarring is more often seen in nonwhite persons.

A patient referred for keloid formation after exci

A patient referred for keloid formation after excision of facial cancer and reconstruction.

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Conversely, insufficient healing can result in a hypotrophic or atrophic scar formation (see image below). All wounds in adult skin heal with a scar. The degree of inflammation has a direct impact on the ultimate scar formation.

A long-standing hypotrophic scar. Patient had abdo

A long-standing hypotrophic scar. Patient had abdominal surgery as a child.

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